EL SEGUNDO, Calif. - Los Angeles Lakers coach Phil Jackson underwent an angioplasty Saturday after experiencing tightness and pain in his chest for about a week.

The procedure to open Jackson's left anterior descending artery lasted more than two hours, team spokesman John Black said.

"There was over 90 percent blockage," Black said. "The main threat would have been a massive heart attack."

Black said a bypass operation wasn't necessary.

It's possible the 57-year-old Jackson will be able to coach today's fourth game of the Western Conference semifinal playoff series against the San Antonio Spurs.

He was to remain at Centinela Hospital Medical Center in nearby Inglewood on Saturday night for observation and is to undergo further tests this morning.

"If all goes well, he'll be able to coach the game," Black said.

Black said it's also possible Jackson will be able to travel to San Antonio on Monday for Game 5 on Tuesday night.

"If all these tests go fine, he'll be cleared to do everything," Black said. "The procedure went very well. He's resting comfortably. He'll be on medication for several months."

Jackson has coached nine championship teams to tie former Boston Celtics coach Red Auerbach for the most in NBA history. Jackson's teams are 161-58 in the postseason for a record .735 winning percentage, and his 161 playoff wins are the most ever.

He coached the Chicago Bulls to six championships in nine years and is going for his fourth title in as many years with the Lakers.

Jackson underwent tests Friday before the Lakers beat San Antonio 110-95, cutting the Spurs' lead to 2-1 in the best-of-seven series.

Doctors wanted to complete all tests Friday, but Jackson decided to wait until after the game. Assistant coach Jim Cleamons ran Saturday's practice and will lead the team today if Jackson can't.

"We all know that he had some concerns," Cleamons said. "We realized he wasn't feeling 100 percent. We're happy and relieved the procedure was successful."